The use of surfactants has become extensive in certain industries and enables otherwise immiscible substances to be mixed successfully. When using surfactants in a water-based system, however, foaming normally occurs. In processes where surfactants are being used for their cleaning properties, e.g., in washing liquids, foaming is acceptable, but in a number of other situations excess foaming is not desired and may interfere with processing or with the end-properties of the product. The processes of papermaking, fermentation, and application of paint all utilize antifoaming agents to reduce foam problems.
Initially kerosine and fuel oils were used to reduce foaming but found to be ineffective and unsatisfactory. More recently a number of different antifoaming agents have been developed for the major processing industries. Generally, antifoaming agents have antifoam components such as silicone-based products, e.g., silicone-coated silica particles, hydrocarbon waxes, or fatty amides or esters, often with a carrier such as a hydrocarbon oil, and if necessary, an emulsifier component.
In the crop protection industry treatment formulations are often sold in concentrated forms for dilution with water by the farmer or user at the site of use. To assist dissolution of the formulation, surfactants are often incorporated into the treatment concentrates and foaming can and often does occur on mixing with water in a spray tank. A small amount of foaming is acceptable, but large scale foaming can give spraying problems. To prevent this the farmer is known to add diesel oil to destabilize the foam. This practice is undesirable as it leads to crop and other areas being sprayed with unrefined fuel oils which is unacceptable from the environmental viewpoint.
Hydrocarbon (e.g. paraffin) oils are also known as anti-foaming additives for formulations of crop protection agents, e.g., from EP-A-0498231 and (East) German Patentschrift 215227. The Applicants have now found that certain specific paraffinic oils can significantly destabilize foam formed in crop protection formulations on dilution in water. Furthermore, the time taken to break the foam with these paraffinic oils is significantly shorter than that found for conventional antifoam agents and for diesel oil.
Certain paraffinic oils of the lubricant oil type, such as the oil available from Shell Petroleum Co., Ltd., under the trade name HVI 60, are known to be useful in crop protection formulations because of their adjuvant effect by which the activity of an active ingredient is enhanced, permitting the use of smaller quantities of the active ingredient to be used. EP-A-356812 discloses an adjuvant composition which comprises surfactant components and optionally a hydrocarbon component. The latter is preferably an aromatic solvent but may be a paraffinic oil or solvent, suitably a solvent-refined petroleum oil fraction composed of paraffinic and naphthenic hydrocarbons and generally having a flash point in excess of 200.degree. C. The hydrocarbon component is believed to exert a minor biochemical effect in use but no antifoaming action is noted, indeed low-foaming surfactants are specifically required for the adjuvant composition.
It has been found by the Applicants that the paraffinic oil adjuvant HVI 60, which has a flash point in excess of 200.degree. C., and an aromatic solvent, SHELLSOL E, have less antifoam action than diesel oil, even at high concentration.
Paraffinic hydrocarbon oils of the type found herein to be useful as antifoam agents have been used in domestic situations because of their low odor and solvent properties, for example SHELLSOL D70 is used as the inert carrier solvent for the insecticide spray SHELLTOX, and have been found to be acceptable by the regulatory authorities.
Recent crop protection formulations have been proposed which utilize surfactants as adjuvants, often in high quantities, see for example EP-A-356812 above. The paraffinic oils specified in the present invention are particularly suited for use with such crop protection formulations and especially formulations including alcohol alkoxylate surfactants which can give rise to significant foaming problems on dilution with water.
The paraffinic oils specified in the present invention may of course be utilized for any antifoaming situation where the paraffinic component fulfills any regulatory requirements and is compatible with the process followed and product prepared.
It is to be understood that the use of the term "antifoaming agent" herein includes an agent which prevents foaming from occurring or controls or removes a foam after formation.